<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://unpkg.com/vue"></script>
</head>
<body>
<div id="app">
    <p v-if="seen">现在你看到我了</p>
</div>
<script>
    var app=new Vue({
        el:'#app',
        data:{
           seen:true
        }
    })
</script>
</body>
</html>